Generally, this invention relates to optical filtration. More specifically, the present invention relates to the reduction of physiologic responses to certain wavelengths of light using notch filters containing nanoparticles.
Various electromagnetic wavelengths can have physical effect on the human body. In particular, certain wavelengths within the visible spectrum are suspected to have negative neurological effects when received by certain photoreceptors in the human eye. Distinct from the rods and cones of the human eye, the melanopsin ganglion cells are also known as intrinsically photoreceptive Retinal Ganglion Cells (ipRGCs) and are intrinsically photoreceptive cells contained in the retina. The cells are connected to certain pain pathways, as well as connected to the suprachiasmatic nucleus. The pain pathways of the thalamus are suspected to affect migraine headaches. Meanwhile, the ipRGCs' interaction with the suprachiasmatic nucleus participates in entrainment of circadian rhythms.
The melanopsin ganglion cells' interaction with pain pathways of the brain have been linked to photophobia. In contrast to the common usage of “phobia,” this is not an irrational fear of light, but rather a physical sensitivity to light. Photophobia has been linked to causing or exacerbating migraine headaches or other light sensitive neurological conditions such as blepharospasm and traumatic brain injury (TBI). The blockage or attenuation of the wavelengths of light that are related to photophobia may have a number of positive benefits. Reducing photophobia in sensitive individuals may lessen or prevent migraine headaches and other negative health effects.
Circadian rhythms are the internal cycles of the body, which approximately synchronize the 24 hour day-night cycles of the earth. Circadian rhythms are important for sleep, moods, and nutrition, as this internal cycle determines when one will feel the need to sleep or eat. They can be very beneficial in keeping the body “on schedule,” but may also become problematic to individuals who do not want their body to align with the local daylight schedule. For example, individuals who travel frequently may be able to avoid the effects of jetlag by preventing changes to their circadian rhythms due to briefly traveling to a locale in a differing time zone. Alternatively, individuals working in professions with non-daylight hour based schedules may want to avoid the effects of the sunlight on their circadian rhythm. For example, a doctor on a night-shift rotation may want to entrain their body with a circadian rhythm irrespective of the light or darkness during the hours they may be awake and active.
To block or attenuate the wavelengths that are negatively neuroactive, the current method is to wear lenses that attenuate light across much of the visible spectrum. This method, however, has significant detriments as the lenses will impair vision in low-light settings and distort colors in nearly all situations. It would be preferable to attenuate the light arriving at the eye only within the narrow range or ranges that are suspected to be neuroactive.
Thus, there are a number of benefits from the selective attenuation or filtering of neuroactive wavelengths of light that can be realized.